Section 2 (3-2) Volcanic Activity

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Vocabulary

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magma chamber- a hole under volcano where the magma is stored.
pipe- a tube which the magma flows.
vent- a big hole on volcano where the lava comes out.
crater- a bowl around the vent which is formed by the explosion of gas.
silica- material formed from oxygen and silicon.
pahoehoe- a kind of lava which moves quickly like liquid, hot lava. When it hardens, it looks like it had been folded and/or squashed.00
aa- a kind of lava which moves slow, and cooler than pahoehoe. When it hardens, the surface is rough.
pyroclastic flow-
active-
dormant-
extinct-
hot spring-
geyser-
geothermal energy-

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Outline

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How Magma Reaches Earth's Surface

• Lava is magma which got out of Earth's surface.
  • Magma is first formed in asthenosphere, where it is under great pressure.
• Magma Rises
  • Liquid magma is less dense from surrounding soil.
  • Liquid magma flows upward into cracks above until it reaches the surface, or gets trapped beneath the layers of rock.
• A Volcano Erupts
  • Dissolved gas gets trapped in magma under a great pressure.
  • The eruption occurs when an opening develop on the surface.
  • When magma reaches the surface, gases bubble out.

Inside a Volcano

• All volcanoes have magma chamber beneath them or near them.
  • In the magma chamber there are some cracks which magma made to force its way.